Trump said that Putin reiterates his denial "every time" and that he seems "very insulted" by the allegations

US president Donald Trump Saturday said he believes Vladimir Putin's assurances that he did not meddle in US elections that propelled him to power, adding the Russian leader felt "very insulted" by the allegations.

Trump, whose key former aides are under a US investigation for alleged collaboration with the Kremlin, said he repeatedly asked Putin about the claims during their chats at the APEC summit in the Vietnamese resort of Danang.

"He (Putin) said he didn't meddle. I asked him again," Trump told reporters on Air Force One as he flew to Hanoi for a state visit.

"You can only ask so many times... He said he absolutely did not meddle in our election," he said, adding he felt Putin seemed "very insulted" by the persistent accusations which he said was "not a good thing for our country".

In May, US intelligence chiefs told Congress they agreed with their analysts' conclusion that Russia did meddle in the election.

But the US president's latest comments suggest he believes staunch Russian denials that the Kremlin played no part in helping him seize the White House -- allegations that have dogged Trump throughout the year since his shock poll win.

Putin also addressed the allegations on Saturday after his meeting with Trump, describing them as a US "domestic political struggle".

"I think these are some sort of fantasies," he told reporters in Danang.

Trump's former campaign chairman Paul Manafort and an associate are under house arrest on charges linked to an investigation by special counsel Robert Mueller into allegations that the campaign colluded with Russia.

Revelations by Facebook and Twitter that Russian-sponsored fake news flooded US social media in the election run-up have further deepened scrutiny on ties between the nations.

Trump and Putin met three times on the margins of the APEC summit, sharing warm handshakes and brief words.

The pair appeared to have struck a chummy tone, with Trump describing a "very good feeling" after the talks, and Putin remarking on the "well-mannered" former reality star.

Asked by reporters on Air Force One if he believed Putin, Trump said he was keen to move on to other issues.

"Look I can't stand there and argue with him," he said. "I'd rather have him get out of Syria, I would rather get to work with him on the Ukraine."

The exchanges produced a rare common ground on the war in Syria, a bloody six-year conflict which has seen the US and Russia back competing factions.

In a joint-statement the leaders said there was "no military solution" to the war, an agreement that marks a small but incremental step towards peace.

American media outlets have also reported that Russia established "troll farms" to produce social media accounts that acted like US citizens in order to skew online conversations about the election.

Such "trolls" reportedly even managed to create real-life demonstrations that further created a feeling of political instability in the country.

America first?

Trump also gave a loud airing to his "America First" rhetoric at the APEC summit.

In a speech on Friday Trump said American jobs had been siphoned off overseas by countries with cheap labor but little compunction to play by trade rules.

"We are not going to let the United States be taken advantage of any more," he said, adding his country would now use its economic might to cut favorable bilateral deals.

China's Xi Jinping laid out a different narrative to the same hall, positioning the world's second largest economy at the heart of the future of global free trade as the US retreats.

As a first mark of an new trade era without the US as its pivot point, 11 Asia-Pacific countries on Saturday agreed to press ahead with the Trans Pacific Partnership (TPP) -- a major agreement abruptly abandoned by Trump at the start of the year.

That dismayed allies and cast into doubt an agreement heralded for tying lower tariffs to strong environmental and labor protections.

After a three-day wrangle that at points threatened to see the massive pact unravel, delegates from economies including Japan, Australia, Canada and Malaysia, agreed to rescue "core elements" of the deal.